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act (up)on something
1. to take action on a particular problem. (Upon is more formal and less commonly used than on.) I will act on this immediately.
2. to take action because of some special information. The police refused to act upon his complaint because he was an ex-convict.
3. to perform on something, usually the stage (in a theater). Ken has never acted on the stage or in front of a camera.
1. Also, act upon. Conduct oneself in accordance with or as a result of information or another action, as in I will act on my lawyer's advice, or The manager refused to act upon the hotel guest's complaints. [c. 1800]
2. Influence or affect, as in The baby's fussing acted on the sitter's nerves. [c. 1800]